Many N-substituted carbamates exhibit physiological activity and are useful as herbicides, insecticides or drugs. Other N-substituted carbamates can be used as intermediates in the phosgene-free synthesis of isocyanates which are widely used in the manufacture of fibers, coatings and other polymeric products.
The most commonly used routes to N-substituted carbamates are the reaction of alcohols with isocyanates and the reaction of alcohols with phosgene and substituted amines (Kuhr et al., "Carbamate Insecticides: Chemistry, Biochemistry, and Toxicology", CRC Press, Cleveland, Ohio, 1976). Although these methods provide the desired carbamates, they require the use of either potentially harmful isocyanates (e.g., methyl isocyanate) or highly toxic phosgene.
Belgian Pat. No. 625,748 discloses the preparation of carbamic acid esters with substitutents on the nitrogen atom by the addition of polymerizable olefins to carbamic acid esters having at least one hydrogen atom on the amine function in the presence of catalysts which react as acids. Specific acids which are disclosed include anhydrous mineral acids, such as hydrofluoric acid, hydrochloric acid, and hydrobromic acid, sulfuric, phosphoric and chlorosulfonic acid, as well as acidic anion exchangers, e.g., those based on polystyrene sulfonic acid and various Lewis acids. Preferably, boron trifluoride or its addition products are utilized.
U.S. Pat. No. 3,520,916 discloses the preparation of N-substituted-N-fluorocarbamates by acid catalyzed addition of an N-fluorocarbamate to an ethylenically unsaturated compound. Mineral acids such as concentrated sulfuric, hydrochloric and phosphoric acids, as well as Friedel-Crafts catalysts such as aluminum trichloride, ferric chloride, stannic chloride and boron trifluoride are disclosed as suitable acid catalysts.
U.S. Pat. No. 4,439,616 discloses the preparation of tertiary aralkyl urethane esters by the reaction of a carbamic acid ester of a lower aliphatic alcohol with an olefin at 40.degree. C.-150.degree. C. in the presence of an acid catalyst, such as sulfuric acid, toluene sulfonic acid, dodecyl benzene sulfonic acid, hydrocarbon sulfate esters, hydrochloric acid, boron trifluoride and other Lewis and Bronsted acids.
U.S. Pat. No. 4,570,012 discloses the preparation of tertiary aralkyl urethanes by reacting tertiary aralkyl diols with lower alkyl esters of carbamic acid in the presence of an acid catalyst to form N-substituted tertiary aralkyl carbamic acid esters. Suitable acid catalysts are sulfuric acid, toluene sulfonic acid, dodecylbenzene sulfonic acid, hydrocarbon sulfate esters, hydrogen chloride, boron trifluoride, and other Lewis and Bronsted acids.
U.S. Pat. No. 4,476,316 discloses the preparation of N-substituted carbamates by reacting a carbamate with an olefin in the presence of a cation exchanger containing sulfonic acid groups and of from 0.1 to 50 g of an alcohol per mole of carbamate starting material.
U.S. Pat. No. 4,578,513 discloses a process for making (phenylisopropyl)urea derivatives by the acid catalyzed addition of substituted ureas to isopropenyl aromatic compounds. The acid catalyst is chosen from concentrated sulfuric acid, a Lewis acid such as boron trifluoride, aluminum chloride or stannic chloride or a substituted sulfonic acid. Preferred acid catalysts include chlorosulfonic acid, p-toluenesulfonic acid, trifluoromethylsulfonic acid, boron trifluoride etherate and sulfuric acid. ##STR1##
U.S. Pat. No. 4,572,804 (Col. 3, lines 35-40) discloses the preparation of geminal bis-carbamates by the acid catalyzed reaction of .alpha., .beta.-unsaturated ethers with carbamates. This reaction was exemplified using p-toluene sulfonic acid. No other acids were disclosed for this reaction. ##STR2##
Fukuoka et al., Japanese Kokoku Patent Publication 61-11942, disclose a process for producing N-substituted carbamate esters, in which cyclohexane and a carbamate ester are reacted in the presence of a supported or unsupported heteropolyacid catalyst. The catalyst is a condensate of a multi-element oxyacid having dissimilar molecules arranged at the center, and has a condensation configuration with polyacid groups of tungsten, molybdenum, vanadium, niobium, etc., which share oxygen. The central elements include phosphorus, arsenic, silicon, germanium, titanium, cerium, thorium, boron, chromium, molybdenum, tungsten, selenium, tellurium, iron, cobalt, nickel manganese, iodine, etc.
U.S. Pat. No. 4,282,368 discloses a process for preparing p-substituted aromatic carbamic acid esters by reacting an aromatic carbamic acid ester with an olefin in the presence of an inorganic acid or a sulfonic acid. ##STR3##
Preferred acid catalysts are organic cation exchangers containing sulfonic acid groups, including perfluorinated sulfonated polystyrene/divinylbenzene resins, perfluorinated, sulfonated crosslinked polystyrene resins and copolymers of tetrafluoroethylene and vinylsulfonic acid. This process provides only the aromatic alkylation product; N-alkylation is not disclosed.
U.S. Pat. No. 4,552,974 discloses the use of organic cation exchange resins having either fluoroalkyl sulfonic acid groups or fluoroalkyl carboxyl groups or both to produce diphenylmethane dicarbamate by reacting an N-phenylcarbamate with a methylenating agent (e.g., formaldehyde).
U.S. Pat. No. 4,176,215 discloses blends of fluorinated polymer which contains sulfonyl groups in ionizable form and a second fluorinated polymer which contains carboxylic acid functional groups. Blends are also disclosed which contain an additional inert polymer such as a copolymer of tetrafluoroethylene and perfluoropropylene.
European Patent Application 291,033 published Nov. 17, 1988, teaches use of perfluorinated acid ion exchange resins containing a group 8 metal in an oxidation state of at least +2 as catalysts for the isomerization of 3-pentenoic compounds to 4-pentenoic compounds. The resins include blends of fluorinated polymers containing sulfonic acid groups and fluorinated polymers containing carboxylic acid groups. Blends are also disclosed which contain copolymers such as tetrafluoroethylene.
U.S. Pat. No. 4,591,439 discloses a polymer blend comprising 75% perfluorocarbon polymer having sulfonyl exchange groups and an equivalent weight of 1100 and 25% copolymer of tetrafluoroethylene and hexafluoropropylene.